Hydraulic releasable stop device for presses and the like



Aug. 12, 1969 R. J. GRAF ET mmmumc RELEASABLE STOP DEVICE FOR PRESSES AND THE LIKE Filed April 28. 1967 5 5 mM% 21 20 55 mGOM NK s m M MW J W M 0L m WW m y 0 A .4 U M g M C Fllr United States Patent 3,460,202 HYDRAULIC RELEASABLE STOP DEVICE FOR PRESSES AND THE LIKE Raymond John Graf, Cincinnati, and Carl William Koors, Harrison, Ohio, assignors to The Cincinnati Shaper Company, Cincinnati, Ohio, a corporation of Ohio Filed Apr. 28, 1967, Ser. No. 634,621 Int. Cl. B29c 3/06 US. Cl. 18-16 4 Claims ABSTRACT OF THE DISCLOSURE A hydraulic stop device for a platen of a compacting press or the like, which under hydraulic pressure can take the entire load of the press and which can be released for ejection purposes by the operation of a valve.

Cross reference to related applications Reference is made to the Belden patent, No. 3,172,156, for an example of a press to which the present invention may be applied. Reference is also made to the Johannigman patent, No. 3,132,378, which discloses a mechanical releasable stop device. The device of the Iohannigman patent can be used for the purpose intended in the press of the Belden patent. The present invention is a hydraulically operated substitute for the lohannigman device and serves the same purpose as the Johannigman device, with the additional advantage of preventing overload during the pressing or ejection cycle.

Background of the invention The invention pertains to the art of releasable stops particularly such as are used in compacting presses to take the full load of the press during the compacting stroke and which can then be released for ejection.

Compacting presses for producing metal articles from powdered metal are known. One such press is disclosed in the said Belden patent. The particular press there disclosed has three platens and during compaction the platens float downwardly by skin friction with the powdered metal being compacted until the respective platens come down against stops. These stops of course determine the configuration of the compacted article. The stops for the respective platens must be capable of taking the entire load of the press. When the compacting stoke is complete, the compacted article is ejected by releasing the several stops in turn, so that the respective platens may move downward to eject the various diameters of the workpiece. Preferably, the top platen moves downwardly until the die contained therein is flush with the die contained in the second platen and then the two dies move downwardly together with their respective platens until they are flush with the third die which is in the bottom platen.

Heretofore, the stop devices for sustaining the entire load of the press during compacting and which are releasable for ejection have been mechanical in character and a mechanical releasable stop device is disclosed and claimed in the aforesaid Iohannigman patent. The device of the present invention is a hydraulically operated substitute for the releasable stop device of the Johannigman patent.

Summary The hydraulically operated releasably stop device of the present invention comprises a high pressure cylinder having a piston therein which constitutes a part of a hollow cylindrical stop rod. Within the cylindrical stop rod a floating piston is provided. Contained in the cylindrical stop rod above the floating piston is low pressure fluid, making the cylindrical stop rod, in effect, an accumulator. Communication may be had between the high pressure ice cylinder and the interior of the stop rod cylinder to the underside of the floating piston through a valve. During the compacting stroke, this valve is closed and the pressure in the high pressure cylinder is greater than the load of the press so that a rigid stop is provided. There ejection means are provided to open the valve, whereby pressure from the high pressure cylinder can pass into the interior of the stop rod cylinder beneath the floating piston. Downward movement of the platen forces the piston assembly down, forcing oil through a valve to the underside of the floating piston, thereby forcing the floating piston upward. Upon the completion of the ejection movement, the fluid pressure on the top side of the floating piston will force oil downwardly through a valve, moving the stop rod back up to its initial position. Spring means will produce valve closure. A pump will then intensify pressure in the high pressure cylinder for the next cycle.

Brief description of the drawing FIG. 1 is a cross sectional view through the hydraulically operated releasable stop device of the present invention with the hydraulic circuit diagrammatically shown and showing the parts in the position of impending stop release.

FIG. 2 is a view similar to FIG. 1 showing the parts when the metal compact is fully ejected.

It should be noted that FIG. 2 is vertically displaced with respect to FIG. 1. The chain line at the bottom of the figures, designated C, is intended to show the common plane.

Description of the preferred embodiment One of the platens of a press which may be of the type disclosed in the Belden patent is indicated at 10-. It will be understood that this platen carries one of the dies used in producing the metal compact. The stop rod is generally indicated at 11. The stop rod 11 comprises a cylindrical member 12 having a top plate 13 and having a piston 114 screwed or otherwise suitably attached to its lower end. The piston 14 operates in a cylinder 15 having the end plate 16 and the annular abutment ring 17. During compacting, pressure in the chamber 18 holds the piston 14 and thus the stop rod 11 in its uppermost position with the upper face of the piston 14 abutting the ring 17. A key 119 cooperating with the slot 20 of the member 12 provides a means of preventing the cylinder from turning relative to the stop rod. The head 13 is provided with a hub 21 having an annular space about the trigger 22 within which a spring 23 is seated. The trigger 22 terminated at its lower end at 24 and a valve element 25 has a shaft 26 which is screwed into the bottom of the trigger 22. A valve element 27 is held on to the trigger 22 by means of the valve element 25 which passes through a bore in the valve 27 with clearance thereabout and the valve member 27 is pushed downwardly away from the trigger 22 by a Belleville spring washer 28. The clearance between the shaft 26 of the valve 25 and the body of the valve 27 communicates with a port 29 and this in turn communicates with the space 30 under the floating piston 31. A port 32 communicates with a passage 33 in the wall of the stop rod 11 and this in turn communicates with a port 34. The head 16 is provided with a passage 35 communicating with a port 36.

The hydraulic circuit comprises the high pressure pump P. The pump is powered by an electric motor 38 and controlled by pressure compensating control 37. The pump P is arranged to pump hydraulic fluid through the check valve 39 into a line 40 which communicates with the port 36 to supply fluid under high pressure to the chamber 18. A relief valve is provided at 41 and its setting is sufliciently high that the pressure in the chamber 18 will be sufficient to withstand the entire load of the press.

The setting of the relief valve provides overload protection for each platen.

Fluid from the port 34 may pass through a line 4-2 back to the pump P, providing the normal supply for the pump. A low pressure relief valve is provided at 43 for protection of the mechanism. 44 indicates a check valve which provides a connection to a sump 46 for an alternate pump supply to make up for leakage in the system. A drain line 45 conveys pump leakage to the sump.

The head 16 is secured to a screw 50 which cooperates with an adjusting nut 51 suitably mounted in the frame of the machine. The adjusting nut may be provided with the annular teeth 52 so that by means of suitable gearing and a crank (see the Belden patent), the location of the stop may be adjusted. It will be understood that rotation of the nut 51 raises or lowers the entire assembly of the cylinder 15, head 16 and ring 17 so as to determine the position at which the platen will stop in its downward movement, during the pressing cycle.

For the purpose of ejection, the trigger 22 is actuated by the ejection rod 60 which is mounted in the next higher platen or on the top platen.

The operation of the stop is as follows. During a compacting stroke, the platen 10, which may be any platen other than the top platen of a press such as the Belden press, floats downwardly until it abuts the plate 13 which constitutes the top of the stop rod 11. The pressure of the press on the platen is transmitted through the plate 13 and the cylinder 12 to the piston 14 and the piston 14 is maintained in the position of FIG. 1 by the high pressure fluid in the chamber 18 supplied by the pump P. Thus, a rigid fixed stop is provided for the platen 10. When the compacting stroke is complete and ejection is to take place, the stop must be released so that the platen 10 may move downwardly to strip the die carried by it from the compacted article. This is accomplished by the action of the ejection rod 60 in moving downward a small amount from the position of FIG. 1 to the position of FIG. 2. Because the ejection rod through the trigger 22 is acting against the high pressure in the chamber 18 in opening the valve 27, the decompression valve 25 is caused to operate first. It will be clear from a study of the figures that the initial movement of the trigger 22 in a downward direction compresses the Belleville spring 28 and thus lifts the head 25a of the decompression valve from its seat and permits fluid to flow through the annular space between the valve stem 26 and the body of the valve 27 and through the port 29 to the space 30. This decompression then makes it possible for further movement of the trigger 22 in a downward direction to lift the valve 27 from its seat to the position shown in FIG. 2 to permit free flow from the chamber 18 into the chamber 30.

It should be noted that the space 70 above the floating piston 31 is supplied with compressed fluid, either gaseous or liquid, through the port 71 by means not shown. Thus, in the condition of FIG. 1 the fluid pressure in the chamber 70 holds the floating piston 31 in its lowermost position and ultimately serves to return the floating piston 31 from the position of FIG. 2 to the position of FIG. 1. It should be noted that the area 30 serves as an acculator section during ejection.

Thus, at the start of ejection the downward movement of the ejection rod 60 transmitted through the trigger 22 opens the decompression valve 25 and thereafter the main valve 27. The fluid in chamber 18 can pass into the chamber 30. Further movement of the platen downwardly forces fluid from the chamber 18 into the chamber 30 against fluid pressure in the chamber 70. This movement brings the parts to the position of FIG. 2 at which time full ejection from the die in the platen 10 is complete. This ejection is accomplished of course by the downward movement of the piston 14, stop rod 11, and platen 10 from the position of FIG. 1 to the position of FIG. 2.

With the load of the press removed from the stop rod 11, the pressure which is required to lift the piston 14, stop rod 11 and platen 10 back to the position of FIG. 1 will be less than the pressure then existing in the chamber 30. Therefore, with the fluid pressure in the chamber 70 and the pressure in the chamber 30, the hydraulic fluid will flow back through the valve 27 into the chamber 18, thus moving the piston 14 and its associated parts back up until the piston 14 abuts the ring 17. During this movement, the floating piston 31 will have returned to its lower position and the spring 23 will raise the trigger 22, thereby closing first the valve 25 and then the valve 27 and thus the mechanism is restored to the position of FIG. 1. The pump will then intensify the pressure in chamber 18 for the next operation.

The stop device of the present invention has been specifically designed for a thousand ton hydraulic compacting press, but it will be understood that it can be built in any desired size to perform the same function.

It will be clear that modifications may be made Within the spirit of the invention and, therefore, no limitation other than as set forth in the claims is intended or should be implied.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a compacting press and the like, wherein a platen must be securely supported to withstand the molding pressure, and then must be released by the action of an ejection rod for ejection of a molded part after a predetermined amount of movement of another part of said press; a cylinder, a piston in said cylinder, a normally closed main valve in said piston, a hollow cylindrical stop rod secured to said piston, the top surface of said stop rod constituting an abutment to stop downward movement of a platen of said press, a trigger secured to said ejection rod and extending through said stop rod and secured to said valve, means urging said trigger and therefore said valve to closed position, and a floating annular piston in said stop rod; means for supplying hydraulic fluid to said cylinder below said piston under a pressure in excess of the molding pressure of the press, and means to supply a fluid under a relatively low pressure to the interior of said stop rod above said floating piston; whereby so long as said valve is closed said stop rod withstands the molding pressure of said press and provides a rigid stop for a platen thereof, and whereby when said valve is opened by said trigger, fluid under pressure from said cylinder passes therethrough into the stop rod between said piston and floating piston to permit said piston and its associated parts to move downwardly, and the accumulated fluid pressure in said stop rod under said floating piston thereafter serves to restore the device to its original condition.

2. Apparatus according to claim 1, wherein said cylinder is rigidly secured to a screw, a rotatable nut cooperating with said screw and axially fixed in said press, whereby rotation of said nut adjusts the position of said' cylinder, and thereby the level at which said platen is stopped.

3. Apparatus according to claim 1, wherein a decompression valve is incorporated in said valve, and means are provided to operate said decompression valve prior to the operation of said main valve to facilitate the opening of said main valve.

4. Apparatus according to claim 3, wherein said main valve has an axial bore and the counterbore at the lower end thereof, a headed pin having a shank of less diameter than said axial bore and a head of less diameter than said counterbore passing through said bore and secured to said trigger, a port communicating between said axial bore and the space above said main valve and means between said trigger and main valve biasing them apart to hold said decompression valve closed.

(References on following page) 5 6 References Cited 3,172,156 3/1965 Belden 18-16.7 3,191,232 6/1965 Haller 18-16.7 UNITED STATES PATENTS 3,337,916 8/1967 Smith 18--16.7 2,762,078 9/1956 Haller 18-165 2,796,633 6/1957 Carlson et a1. 18-16.5 RD FLINT, 1a., Pnmary Exammer 3,132,379 5/1964 Crane 18-16.5 us, :1, R,

3,168,759 2/1965 Johannigman 1816.7 13-16 Patent No. 3,6U ,202 Dated August 12, 1969 Inventor) Raymond John Graf and Carl William Koors It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 56, after "with" and before "compressed" insert a same line, after "compressed" insert gas Column 3 line 56 and 57, cancel "fluid, either gaseous or liquid,".

Column 3, line 63, "culator" should be cumulator Column 4 (Claim 1) line 52, after "fluid" insert under "iii? Aim f u: Li- H) no NM 11510 Attest:

EdwardM-Fletcheqln Amsfing Officer wmuu n. suuuxm, JR.

Commissioner of Patents 

